The present invention relates broadly to the field of digital data recording and retrieving from a magnetic disk and particularly to a cartridge for use in a digital magnetic disk drive for storing and retrieving data.
Disk storage devices having been used in digital computer systems as a means to provide random access bulk data storage. Not infrequently, such disk drives are designed with a recording media disk permanently mounted on a spindle and rotated by a motor. Read/write heads are mounted to move radially with respect to the disk, thereby permitting the drive to either store or retrieve data from tracks on the storage media. These tracks are disposed in concentric ring-like regions on the surface of the disk.
Fixed disk storage media of the type described are usually quite expensive but do provide a great deal of random access storage. A disadvantage of such drives, however, is that the storage media is not removable, so the storage space available becomes dedicated to certain tasks on the system to which the drive is attached and, therefore, unavailable for other uses. Such drives also require backup capability to protect against the various types of failures which may occur.
To solve the problem of disk dedication, removable media disks have been developed. In some such devices, a plurality of disks are affixed to a shaft. The disks, prior to being mounted in the drive, are frequently housed in a dust-proof case. When in the drive, the disks are surrounded by a drive closure which keeps out as much airborne contamination as possible. Disk packs of this sort have usually been quite large in storage size and also quite expensive, although they have made available a way to provide changeable media for large capacity disk storage devices.
There has been a disk pack sold by IBM Corporation under the designation number 3336. That disk pack has an open bottom and axially disposed, radially flexing members used for centering with respect to the drive spindle.
In an effort to reduce the cost of disk storage devices, interchangeable flexible media disk drives (floppy disk) have been developed. While use of such devices with interchangeable flexible storage media has reduced the cost of bulk storage for small systems, the reliability due to wear and contamination is considerably lower than that for the rigid disk drives. Disk centering is also a problem. In addition, the amount of storage available for such flexible disk drives is small compared to the other systems described earlier.
An approach for increasing the storage capacity and overcoming the reliability problems is the so called Winchester drive. One of the first such drives developed had an interchangeable cartridge in which heads and the disks were removable as a unit. In use, however, there were few cartridges used in addition to the cartridge sold with the drive so later drives were developed using Winchester technology which did not have removable storage media. This approach does suffer from the same defect as the first mentioned drive, namely, that the storage area of the disk becomes dedicated and no longer available for other uses.
As is recognized by those of skill in the art, there is a need to backup all types of disk storage devices for various reasons, such as to protect from system failures, software failures, etc. One approach to solving the backup problem is to use another disk. Using another disk for backup purposes, however, is not cost effective, even though it is an easy way to provide the necessary backup. Another backup approach is to use a tape system. Using a tape system as a backup is less expensive than using another disk, but the speed of such systems is not generally compatible with a disk, so tape backup is not the easiest to implement and is more costly than is desirable.